Transport Layer Fairness and Congestion Control in Wireless Ad Hoc Access Networks

Transmission Control Protocol (TCP) is a reliable, end-to-end transport protocol, which is most widely used for data services and is very efficient for wired networks. However, experiments and research showed that TCP's congestion control algorithm performs very poorly over Wireless Ad Hoc Networks with degraded throughputs and severe unfairness among flows. This thesis studies fairness and throughput issues presented by TCP in Wireless Ad Hoc Access Networks, which are Wireless Ad Hoc Networks with supporting infrastructure, i.e. gateway, to send and receive packets from wired networks, and concentrates on designing an applicable congestion control algorithm based on the characteristics of the Wireless Ad Hoc Access Networks. We proposed using DCCP (Datagram Congestion Control Protocol) with a specially designed congestion control algorithm and implemented this congestion control algorithm on NS2. Simulations were performed and the results show the improvements on fairness and throughput achieved by using the designed congestion control algorithm. The two flows with the new congestion control tested in the simulation had Jain's fairness index greater than 0.95 in all combinations, where TCP flows may have a fairness index less than 0.6. The aggregate throughputs of the two flows with our new congestion control algorithm also increased. iii ACKNOWLEDGEMENT